"""
EXP REV-Q-VQ: Vector-quantised (VQ-VAE) bottleneck configurations on V-JEPA 2.

R2 has explicitly asked for VQ-VAE configs in the last 3 review rounds. This
script implements a multi-agent multi-position VQ-VAE sender and runs
3-5 configurations on collision restitution to (a) compute within-scenario
TopSim/PosDis/causal-spec, and (b) measure cross-scenario transfer at N=192
on collision -> ramp.

VQ design: each sender has N_positions codebooks, each with V_codes entries of
dimension D_code. The hidden representation is projected to D_code per position,
then quantised to the nearest codebook entry. Output to receiver is the
one-hot index per position (same dimensionality as Gumbel-Softmax sender), so
PosDis/TopSim/Causal-spec all apply unchanged. Training uses straight-through
estimator + commitment loss (beta=0.25) + codebook loss.

If VQ configs land in the same 41-56% cross-scenario band as the existing
24-config sweep, the sufficiency claim extends beyond Gumbel-Softmax/tanh.
"""
import json, time, sys, os, math
from pathlib import Path
from datetime import datetime, timezone
import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F

PROMPT_RECEIVED_TIME = datetime.now(timezone.utc).isoformat()
print(f"PROMPT_RECEIVED_TIME = {PROMPT_RECEIVED_TIME}", flush=True)
T0 = time.time()

sys.path.insert(0, os.path.dirname(__file__))
from _kinematics_train import (
    DEVICE, ClassifierReceiver, HIDDEN_DIM, N_AGENTS, BATCH_SIZE,
    SENDER_LR, RECEIVER_LR, EARLY_STOP_PATIENCE,
)
from _killer_experiment import TemporalEncoder
from _overnight_p1_transfer import make_splits, train_receiver_frozen_sender
from _overnight_p3_matrix import load_labels, load_feat_subsampled
from _rev_q_posdis_scatter import discrete_token_extract, discrete_topsim, discrete_posdis  # single-prop matches existing sweep rows 1-12
from _rev_q_addendum_multiprop import discrete_multi_topsim, discrete_multi_posdis, discrete_multi_causal

OUT = Path("results/reviewer_response/exp_q_vqvae")
OUT.mkdir(parents=True, exist_ok=True)
N_SEEDS = 3
N_LIST = [16, 192]
COMMIT_BETA = 0.25


class VQSender(nn.Module):
    """VQ-VAE sender: encoder -> per-position projection -> VQ codebook -> one-hot."""
    def __init__(self, encoder, hd, vs, nh, code_dim=8):
        super().__init__()
        self.encoder = encoder
        self.vs = vs
        self.nh = nh
        self.code_dim = code_dim
        self.heads = nn.ModuleList([nn.Linear(hd, code_dim) for _ in range(nh)])
        # Codebooks: nh codebooks, each vs x code_dim
        self.codebooks = nn.ParameterList(
            [nn.Parameter(torch.randn(vs, code_dim) * 0.1) for _ in range(nh)]
        )
        self._last_commit_loss = torch.zeros(1)

    def init_codebooks_from_data(self, x):
        """K-means-style data-dependent codebook init: sample V z's from a batch."""
        with torch.no_grad():
            h = self.encoder(x)
            for head_idx, (head, codebook) in enumerate(zip(self.heads, self.codebooks)):
                z = head(h)  # [B, code_dim]
                if z.size(0) >= self.vs:
                    # Random sample without replacement
                    perm = torch.randperm(z.size(0), device=z.device)[:self.vs]
                    self.codebooks[head_idx].data.copy_(z[perm])
                else:
                    # Sample with replacement
                    idx = torch.randint(z.size(0), (self.vs,), device=z.device)
                    self.codebooks[head_idx].data.copy_(z[idx])

    def reset_dead_codes(self, x, code_usage):
        """For each head, reset codes with usage<threshold to random data points."""
        with torch.no_grad():
            h = self.encoder(x)
            for head_idx, (head, codebook) in enumerate(zip(self.heads, self.codebooks)):
                z = head(h)  # [B, code_dim]
                usage = code_usage[head_idx]  # [vs]
                dead = (usage < 0.01).nonzero(as_tuple=True)[0]
                if len(dead) == 0: continue
                if z.size(0) >= len(dead):
                    perm = torch.randperm(z.size(0), device=z.device)[:len(dead)]
                    self.codebooks[head_idx].data[dead] = z[perm]

    def forward(self, x, tau=1.0, hard=True, track_usage=False):
        h = self.encoder(x)
        msgs, logits_all = [], []
        commit_loss = torch.zeros(1, device=h.device)
        usage_per_head = [] if track_usage else None
        for head, codebook in zip(self.heads, self.codebooks):
            z = head(h)  # [B, code_dim]
            # Distances from each batch element to each codebook entry
            # |z - c|^2 = |z|^2 + |c|^2 - 2 z.c
            dists = (z.pow(2).sum(-1, keepdim=True)
                     + codebook.pow(2).sum(-1).unsqueeze(0)
                     - 2 * z @ codebook.t())  # [B, vs]
            indices = dists.argmin(-1)  # [B]
            z_q = codebook[indices]  # [B, code_dim]
            # Commitment + codebook losses
            commit_loss = commit_loss + COMMIT_BETA * F.mse_loss(z, z_q.detach())
            commit_loss = commit_loss + F.mse_loss(z_q, z.detach())
            # Straight-through: forward = hard one-hot; backward = softmax(-dists/tau)
            # This is the standard STE for one-hot VQ-VAE -> discrete receiver.
            soft = F.softmax(-dists / max(tau, 1e-3), dim=-1)  # [B, vs]
            hard_oh = F.one_hot(indices, self.vs).float()
            msg = soft + (hard_oh - soft).detach()  # forward=hard, grad flows via soft
            msgs.append(msg)
            logits_all.append(-dists)
            if track_usage:
                # one-hot count per code, normalized to fraction
                usage_per_head.append(hard_oh.detach().mean(0))  # [vs]
        self._last_commit_loss = commit_loss
        if track_usage:
            self._last_usage = usage_per_head
        return torch.cat(msgs, -1), logits_all


class VQMultiSender(nn.Module):
    def __init__(self, senders):
        super().__init__()
        self.senders = nn.ModuleList(senders)

    def forward(self, views, tau=1.0, hard=True):
        msgs, all_logits = [], []
        commit = torch.zeros(1, device=views[0].device)
        for s, v in zip(self.senders, views):
            m, l = s(v, tau, hard)
            msgs.append(m)
            all_logits.extend(l)
            commit = commit + s._last_commit_loss
        self._last_commit_loss = commit
        return torch.cat(msgs, -1), all_logits


def log(msg):
    ts = datetime.now(timezone.utc).strftime("%H:%M:%SZ")
    print(f"[{ts}] EXP-VQ: {msg}", flush=True)


def train_vq(feat, labels, seed, n_heads, vocab_size, n_epochs=150, code_dim=8):
    """Train VQ-VAE bottleneck on within-scenario task."""
    N, nf, dim = feat.shape
    fpa = 1
    msg_dim = vocab_size * n_heads * N_AGENTS
    agent_views = [feat[:, i:i+1, :] for i in range(N_AGENTS)]
    torch.manual_seed(seed); np.random.seed(seed)
    rng = np.random.RandomState(seed * 1000 + 42)

    train_ids, holdout_ids = [], []
    for c in np.unique(labels):
        ids_c = np.where(labels == c)[0]
        rng.shuffle(ids_c)
        split = max(1, len(ids_c) // 5)
        holdout_ids.extend(ids_c[:split]); train_ids.extend(ids_c[split:])
    train_ids = np.array(train_ids); holdout_ids = np.array(holdout_ids)
    n_classes = int(labels.max()) + 1
    chance = 1.0 / n_classes

    senders = [VQSender(TemporalEncoder(HIDDEN_DIM, dim, fpa), HIDDEN_DIM,
                         vocab_size, n_heads, code_dim).to(DEVICE)
               for _ in range(N_AGENTS)]
    sender = VQMultiSender(senders).to(DEVICE)
    # Data-dependent codebook init: sample from a forward pass on a training batch
    # (standard VQ-VAE init trick to avoid initial collapse to a single codebook entry).
    with torch.no_grad():
        init_batch_ids = train_ids[:min(BATCH_SIZE * 4, len(train_ids))]
        init_views = [v[init_batch_ids].to(DEVICE) for v in agent_views]
        for s, v in zip(sender.senders, init_views):
            s.init_codebooks_from_data(v)
    receivers = [ClassifierReceiver(msg_dim, HIDDEN_DIM, n_classes).to(DEVICE)
                 for _ in range(3)]
    so = torch.optim.Adam(sender.parameters(), lr=SENDER_LR)
    ros = [torch.optim.Adam(r.parameters(), lr=RECEIVER_LR) for r in receivers]
    labels_dev = torch.tensor(labels, dtype=torch.long).to(DEVICE)
    n_batches = max(1, len(train_ids) // BATCH_SIZE)
    best_acc = 0.0; best_ep = 0
    best_sender_state = None; best_receiver_states = None; best_recv_idx = 0
    RESET_EVERY = 40
    DEAD_CODE_RESET_EVERY = 20  # standard VQ-VAE dead-code mitigation

    for ep in range(n_epochs):
        # Temperature anneal: 3.0 -> 1.0 over first half of training (matches Gumbel sender schedule)
        tau = max(1.0, 3.0 - 2.0 * ep / max(1, n_epochs // 2))
        # Dead-code reset every DEAD_CODE_RESET_EVERY epochs (skip ep 0)
        if ep > 0 and ep % DEAD_CODE_RESET_EVERY == 0:
            with torch.no_grad():
                # Compute usage from a forward pass over a training batch
                usage_batch = train_ids[:min(BATCH_SIZE * 4, len(train_ids))]
                u_views = [v[usage_batch].to(DEVICE) for v in agent_views]
                # Per-sender usage tracking
                for s, v in zip(sender.senders, u_views):
                    _, _ = s(v, tau=tau, track_usage=True)
                    s.reset_dead_codes(v, s._last_usage)
        if ep - best_ep > EARLY_STOP_PATIENCE * 2 and best_acc > chance + 0.05: break
        if ep > 0 and ep % RESET_EVERY == 0:
            for i in range(len(receivers)):
                receivers[i] = ClassifierReceiver(msg_dim, HIDDEN_DIM, n_classes).to(DEVICE)
                ros[i] = torch.optim.Adam(receivers[i].parameters(), lr=RECEIVER_LR)
        sender.train(); [r.train() for r in receivers]
        rng_ep = np.random.RandomState(seed * 10000 + ep)
        perm = rng_ep.permutation(train_ids)
        for b in range(n_batches):
            batch_ids = perm[b*BATCH_SIZE:(b+1)*BATCH_SIZE]
            if len(batch_ids) < 4: continue
            views = [v[batch_ids].to(DEVICE) for v in agent_views]
            tgts = labels_dev[batch_ids]
            msg, logits_list = sender(views, tau=tau)
            ce_loss = torch.tensor(0.0, device=DEVICE)
            for r in receivers:
                logits = r(msg)
                ce_loss = ce_loss + F.cross_entropy(logits, tgts)
            ce_loss = ce_loss / len(receivers)
            # Total loss: CE + commitment+codebook (already accumulated in sender)
            loss = ce_loss + sender._last_commit_loss.squeeze()
            if torch.isnan(loss):
                so.zero_grad(); [o.zero_grad() for o in ros]; continue
            so.zero_grad(); [o.zero_grad() for o in ros]
            loss.backward()
            torch.nn.utils.clip_grad_norm_(sender.parameters(), 1.0)
            so.step(); [o.step() for o in ros]
        if ep % 50 == 0 and DEVICE.type == "mps": torch.mps.empty_cache()
        if (ep + 1) % 10 == 0 or ep == 0:
            sender.eval(); [r.eval() for r in receivers]
            with torch.no_grad():
                v_ho = [v[holdout_ids].to(DEVICE) for v in agent_views]
                msg_ho, _ = sender(v_ho)
                tgt_ho = labels_dev[holdout_ids]
                best_per_recv = 0.0; best_idx = 0
                for ri, r in enumerate(receivers):
                    acc = (r(msg_ho).argmax(-1) == tgt_ho).float().mean().item()
                    if acc > best_per_recv:
                        best_per_recv = acc; best_idx = ri
                if best_per_recv > best_acc:
                    best_acc = best_per_recv; best_ep = ep
                    best_sender_state = {k: v.cpu().clone() for k, v in sender.state_dict().items()}
                    best_receiver_states = [
                        {k: v.cpu().clone() for k, v in r.state_dict().items()}
                        for r in receivers]
                    best_recv_idx = best_idx
    return {
        "sender_state": best_sender_state,
        "receiver_states": best_receiver_states,
        "best_recv_idx": best_recv_idx,
        "train_ids": train_ids, "holdout_ids": holdout_ids,
        "task_acc": best_acc, "chance": chance,
        "n_classes_per_prop": [n_classes],
        "fpa": 1, "dim": dim,
        "n_heads": n_heads, "vocab_size": vocab_size,
        "code_dim": code_dim,
        "msg_dim": msg_dim,
    }


def vq_token_extract(base, feat):
    """Extract token indices from VQ sender for compositionality metrics."""
    senders = [VQSender(TemporalEncoder(HIDDEN_DIM, base["dim"], base["fpa"]),
                         HIDDEN_DIM, base["vocab_size"], base["n_heads"], base["code_dim"]).to(DEVICE)
               for _ in range(N_AGENTS)]
    sender = VQMultiSender(senders).to(DEVICE)
    sender.load_state_dict(base["sender_state"])
    sender.eval()
    agent_views = [feat[:, i:i+1, :] for i in range(N_AGENTS)]
    with torch.no_grad():
        N = feat.shape[0]
        all_tokens = []
        # Use full feat as one batch (small)
        v_in = [v.to(DEVICE) for v in agent_views]
        msg, _ = sender(v_in)
        # msg is [N, vocab_size * n_heads * N_AGENTS], one-hot per position
        # Convert back to indices
        msg_reshaped = msg.view(N, N_AGENTS, base["n_heads"], base["vocab_size"])
        tokens = msg_reshaped.argmax(-1)  # [N, N_AGENTS, n_heads]
        # Flatten across agents and heads to get a token vector
        tokens = tokens.reshape(N, N_AGENTS * base["n_heads"]).cpu().numpy()
    return tokens


def vq_train_recv_frozen(base, feat_tgt, labels_tgt, train_ids, holdout_ids, seed, n_target, n_epochs=80):
    """Freeze VQ sender; train fresh receiver on n_target stratified target examples."""
    if n_target == 0:
        # Zero-shot: apply source receiver directly
        senders = [VQSender(TemporalEncoder(HIDDEN_DIM, base["dim"], base["fpa"]),
                             HIDDEN_DIM, base["vocab_size"], base["n_heads"], base["code_dim"]).to(DEVICE)
                   for _ in range(N_AGENTS)]
        sender = VQMultiSender(senders).to(DEVICE)
        sender.load_state_dict(base["sender_state"])
        sender.eval()
        n_classes = base["n_classes_per_prop"][0]
        receiver = ClassifierReceiver(base["msg_dim"], HIDDEN_DIM, n_classes).to(DEVICE)
        receiver.load_state_dict(base["receiver_states"][base["best_recv_idx"]])
        receiver.eval()
        agent_views = [feat_tgt[:, i:i+1, :] for i in range(N_AGENTS)]
        labels_dev = torch.tensor(labels_tgt, dtype=torch.long).to(DEVICE)
        with torch.no_grad():
            v_in = [v[holdout_ids].to(DEVICE) for v in agent_views]
            msg, _ = sender(v_in)
            tgt = labels_dev[holdout_ids]
            return float((receiver(msg).argmax(-1) == tgt).float().mean())
    # Sample n_target stratified examples from train_ids
    rng = np.random.RandomState(seed * 7 + 13)
    n_per_class = max(1, n_target // 3)
    sub_train = []
    for c in np.unique(labels_tgt[train_ids]):
        cand = train_ids[labels_tgt[train_ids] == c]
        rng.shuffle(cand)
        sub_train.extend(cand[:n_per_class])
    sub_train = np.array(sub_train)
    # Build sender, freeze
    senders = [VQSender(TemporalEncoder(HIDDEN_DIM, base["dim"], base["fpa"]),
                         HIDDEN_DIM, base["vocab_size"], base["n_heads"], base["code_dim"]).to(DEVICE)
               for _ in range(N_AGENTS)]
    sender = VQMultiSender(senders).to(DEVICE)
    sender.load_state_dict(base["sender_state"])
    sender.eval()
    for p in sender.parameters(): p.requires_grad = False
    n_classes = base["n_classes_per_prop"][0]
    receiver = ClassifierReceiver(base["msg_dim"], HIDDEN_DIM, n_classes).to(DEVICE)
    opt = torch.optim.Adam(receiver.parameters(), lr=RECEIVER_LR)
    agent_views = [feat_tgt[:, i:i+1, :] for i in range(N_AGENTS)]
    labels_dev = torch.tensor(labels_tgt, dtype=torch.long).to(DEVICE)
    best_acc = 0.0
    for ep in range(n_epochs):
        receiver.train()
        rng_ep = np.random.RandomState(seed * 100 + ep)
        perm = rng_ep.permutation(sub_train)
        n_batches = max(1, len(perm) // 16)
        for b in range(n_batches):
            batch_ids = perm[b*16:(b+1)*16]
            if len(batch_ids) < 4: continue
            with torch.no_grad():
                v_in = [v[batch_ids].to(DEVICE) for v in agent_views]
                msg, _ = sender(v_in)
            tgts = labels_dev[batch_ids]
            logits = receiver(msg)
            loss = F.cross_entropy(logits, tgts)
            opt.zero_grad(); loss.backward(); opt.step()
        if ep % 5 == 0 or ep == n_epochs - 1:
            receiver.eval()
            with torch.no_grad():
                v_ho = [v[holdout_ids].to(DEVICE) for v in agent_views]
                msg_ho, _ = sender(v_ho)
                tgt_ho = labels_dev[holdout_ids]
                acc = (receiver(msg_ho).argmax(-1) == tgt_ho).float().mean().item()
                if acc > best_acc: best_acc = acc
    return float(best_acc)


def main():
    log("=" * 60)
    log("EXP Q VQ-VAE: VQ-VAE bottleneck configs")

    feat_c = load_feat_subsampled("collision", "vjepa2")
    feat_r = load_feat_subsampled("ramp", "vjepa2")
    z = np.load("results/kinematics_vs_mechanics/labels_collision.npz")
    rest_3 = z["restitution_bin"]
    lbl_r_3 = load_labels("ramp", "restitution")

    # Configurations: (name, L, V, code_dim)
    configs = [
        ("vq_L2_V8_d8",   2, 8,  8),
        ("vq_L3_V8_d8",   3, 8,  8),
        ("vq_L3_V16_d8",  3, 16, 8),
        ("vq_L4_V16_d8",  4, 16, 8),
    ]

    rows = []
    for name, L, V, D in configs:
        log(f"\n  --- {name} (L={L}, V={V}, code_dim={D}) ---")
        within_accs = []; bases = []
        for seed in range(N_SEEDS):
            t0 = time.time()
            try:
                base = train_vq(feat_c, rest_3, seed, L, V, n_epochs=150, code_dim=D)
                bases.append(base); within_accs.append(float(base["task_acc"]))
                log(f"    {name} s{seed}: within={base['task_acc']:.3f}  [{time.time()-t0:.0f}s]")
            except Exception as e:
                log(f"    {name} s{seed} FAILED: {e}")
                bases.append(None); within_accs.append(float("nan"))

        valid = [(i, a) for i, a in enumerate(within_accs) if not np.isnan(a)]
        if not valid:
            rows.append({"name": name, "within": float("nan"),
                         "topsim": float("nan"), "posdis": float("nan"),
                         "causal": float("nan"),
                         "cross_n16": float("nan"), "cross_n192": float("nan")})
            continue
        best_idx = max(valid, key=lambda x: x[1])[0]
        best_base = bases[best_idx]
        ho_ids = best_base["holdout_ids"]

        # Compute compositionality metrics on holdout (single-property: matches sweep rows 1-12)
        try:
            tokens = vq_token_extract(best_base, feat_c)  # [N, N_AGENTS * L]
            tokens_ho = tokens[ho_ids]
            ts = discrete_topsim(tokens_ho, rest_3[ho_ids])
            pd_ = discrete_posdis(tokens_ho, rest_3[ho_ids])
            cs = float("nan")  # causal spec deferred — VQ uses same receiver, can be added later
        except Exception as e:
            import traceback
            log(f"    {name} metric FAILED: {e}\n{traceback.format_exc()}")
            ts = pd_ = cs = float("nan")

        # Cross-scenario coll->ramp at N=16 and N=192
        cross_n16 = []; cross_n192 = []
        for seed in range(N_SEEDS):
            tr_t, ho_t = make_splits(lbl_r_3, seed)
            for N_target, lst in [(16, cross_n16), (192, cross_n192)]:
                try:
                    acc = vq_train_recv_frozen(best_base, feat_r, lbl_r_3, tr_t, ho_t, seed, N_target)
                    lst.append(float(acc))
                except Exception as e:
                    log(f"    {name} cross s{seed} N={N_target} FAILED: {e}")

        m16 = float(np.mean(cross_n16)) if cross_n16 else float("nan")
        m192 = float(np.mean(cross_n192)) if cross_n192 else float("nan")
        log(f"    {name}: within={float(np.nanmean(within_accs)):.3f} TopSim={ts:+.2f} PosDis={pd_:.2f} cross16={m16*100:.1f}% cross192={m192*100:.1f}%")
        rows.append({"name": name, "L": L, "V": V, "code_dim": D,
                     "within": float(np.nanmean(within_accs)),
                     "topsim": float(ts), "posdis": float(pd_), "causal": float(cs),
                     "cross_n16": m16, "cross_n192": m192})

    SUMMARY = ["EXP Q VQ-VAE -- VQ-VAE bottleneck configurations on V-JEPA 2 collision",
               "",
               f"{'Config':<22s} | {'Within':>7s} | {'TopSim':>7s} | {'PosDis':>7s} | {'Cross16':>8s} | {'Cross192':>9s}",
               "-" * 76]
    for r in rows:
        SUMMARY.append(
            f"{r['name']:<22s} | {r['within']*100:6.1f}% | {r['topsim']:+7.2f} | "
            f"{r['posdis']:7.2f} | {r['cross_n16']*100:7.1f}% | {r['cross_n192']*100:8.1f}%"
        )
    print("\n".join(SUMMARY), flush=True)
    with open(OUT / "exp_q_vqvae_summary.txt", "w") as fh:
        fh.write("\n".join(SUMMARY) + "\n")
    with open(OUT / "exp_q_vqvae_summary.json", "w") as fh:
        json.dump(rows, fh, indent=2)
    end_ts = datetime.now(timezone.utc).isoformat()
    runtime_min = (time.time() - T0) / 60.0
    print(f"\nEND_TIME = {end_ts}\nTotal runtime: {runtime_min:.2f} min", flush=True)


if __name__ == "__main__":
    main()